Electronic automatic sequence timers



July 22, 1958 T. .NlcKERsON 2,844,211 ELECTRONIC AUTOMATIC SEQUENCE TIMERS v Filed-Aug. 25, 1955 ffl/e UnitedV States This invention relates Ito seismics'urveying apparatus and-more particularly toY an electronic automatic sequence-.timer for controlling certain events of a seismic operation.

Apparatus generally used in seismic surveying includesv an, explosive assembly for creating seismic waves which are transmitted through the earths formations, one or moredetectors which are set'on the earths surface to detect the'seismic waves and to transform them into corresponding electrical seismic signals and a recording mechanism, for example, vanV oscillograph, for producing a permanent record of the seismcsignals.- The recordingrmechanism generally includes a recording medium,`

e.v g.,photographic film, whichti's driven byl amotor, and agalvanometric device, which is responsive to the seismic signals andwhichincludes one or more coils each having al mirror attached thereto and associated lamps, for recording the seismic signals on the recording medium.

The Arecording mechanism may also include mixingcircuits to` mix the seismic signals from two or more de, ',tectorsprior to recording 4to produce moreintelligible traces, on the recording medium and means for-decreasing theamplitudefof the incoming seismic signals during arent the actual kiiring'in order to prevent overloading the apjparatus. -Means for decreasing the amplitude of the in? coming lsignals may, for example, include an amplifier havingfa gain control device or-an appropriate shunt connected' across the input of the recording mechanism.

When a given area of land is being surveyed the explosive'assembly is used to create seismic waves at each of a large number vof predetermined shotpoints which are, spaced apartv in rlines at regular intervals.k A record of'the seismic waves emanatingfrom each shotpoint is j recorded on a separate strip of the photographic iilm and ythereafter a cross section of the earths structural formations is plotted along the lines. By combining the infor-` mation from'several lines a contour map may be drawn which shows ntheelevation of the geologicalformations. This survey is made'in the hope of revealing formations whichfare favorable for the-accumulation of oil. As can be readily seen a large number of records each of which must be clearly'identiiie'd, e. g., asto location of v shotpoint, are needed to `produce suicientginforniation tov draw a Ycontour map. In order to identify each reci 1 ord, a portion of each photographic strip is used; for re Acording a title which may include not only the geograph-l* Patented July 22, 1958 ICQ at the beginning of the strip prior to the point of the trace' which indicates the instant at which the shot was iired or at the end of the strip after all intelligible or desired signals have been received. However, in seismicsurveying practice, it is customary to place the title block at the beginning of the strip. i

In a seismic surveying operation, it Vis generally desired to have certain events occur in a given sequencev and for a given interval of time at each shotpoint. After providing space on the photographic strip yfor a title block, a charge is detonated at the shotpoint, strong primary waves are transmittedy through the earth, detected and recorded, and then reflected waves from the subsurface formations are detected and recorded. It is often desirablel to protect the oscillograph from the strong primary waves by decreasingthe amplitude of lthese waves at the seismic signal input to the os'cillographand'to mix the reflected seismic signals received from two lor more detectors to. produce a clear trace'onL theplioto'- graphic strip.

It is an object of this invention to providefapparatus'vr for vautomatically controlling kcertain events ofa .seismic surveying operation.

It is also an object of this invention to electronicallyv seismic 'records which are clear, uniform and of a standconvenience in handling andstoring' ardized length` for same."

-For other objects and fora better understanding of the Y inventionreference may be'had to the drawing in which vthe single iigureis a schematic diagram, partly in block form, of one embodiment'ofthe' invention. t

In accordance with this invention an electronic auto'- matic sequence timer isprovided to automatically c'ause certain events of a seismic surveying operation to occur v sequenceand for a predeterminedinterval `of Vi 'has its eii'eirgizing winding connected across izvolt` -battery ztvia' a master svvitciia. Afresistorc'apaeitor-ercuit 45 is connected across the l2-vlt battery ,2 -viacorifacts of master relay 1 and anaiiiiiiia'iy Switchs. g Tlie' resistor-capacitor circuit 4 is ,also kethnieCted `between v the control grid andthe cathode' ofw'aidischarge device ical location of the shot but also the date, the charge size, etc. the seismic record is to merely stamp the title onto the record. However, if no means are provided to render a portion of the stripv of photographic paper unexposed, l

4trace lines will pass through the title making it diiiicult y' to: read the information which it contains.V Another Way Y,

torecord'rthettitle on the seismic record is to paste a title tainusefl information. This latter method providesv a One of the easiest ways to record'a title on v having anioniable medium, for example, a thyratron 6.1,- Theanode of thyratr'on connected tlirotighthe ener-l gilzing' winding oflight'relay 7 andthe'contactjs of VrriasterV relayjl tojapositivegterminal of a`4 5-volt batteryA 8y which.. hasY its'negative terminal eonnecfedj tothe' positive'iter-'- minalof the Vi12-volt battery'Z. L

Contacts of thepiigiit reiay'i md niej aiiiiiii'ary wife-ir 5 eonneestiie 12-vc1t battery araeress .galvsnenieter of well-known types. A commontypeof `'oscillt'i'graph usedtin seismic operations includes'a reel of phbiographiek iilm ,whichris iihr'eeled by a motor uponrdeniahd vand a seismic signalA circuit which may include a gaivanofnetiic device khaving mirrors adapted to beA responsive 4t'ofiief A seisniiemsignais received; from A detectors or geophenes and lamps positionedjte reecta beamn of light fro'rreacli of the mirrors onto the photographic iilm. In addition, the signal circuit may include an amplifier having a gain control device or a shunt disposed across the input to the galvanometricV device during actual tiring to limit the amplitude or the signal applied thereto in order to prevent overloading the galvanometric device. Mixing circuits may also be included in the signal circuit to produce a clearer seismic signal by mixing the signals derived from two or more detectors.

A resistor-capacitor circuit is connected across the l2-volt battery 2 via contacts of light relay 7 and auxiliary switch 5. Furthermore, resistor-capacitor circuit 10 is connected between `the control grid `and the cathode of a discharge device, for example a thyratron 11. The anode of the thyratron 11 is connected to the positive terminal of the 45-volt battery 8 via the energizing winding of auxiliary relay 12 and contacts of master relay l. The energizing winding of 4lire relay 13 is connected across the l2-volt battery 2 via contacts of the auxiliary relay 12 and auxiliary switch 5. An explosive assembly 14 is connected to the contacts of iire relay 13. A resistorcapacitor circuit 15 is connected across the l2-volt battery 2 via contacts of tire relay 13 and auxiliary switch 5. The resistor-capacitor circuit 15 is also connected between the control grid and the cathode of a discharge device, for example, a thyratron 16. The anode of thyratron 16 is connected via the energizing winding of a signal circuit relay 17 and the contacts of master relay 1 to the positive terminal of the 45-volt battery 8. The seismic signal circuit of the oscillograph 9 is connected to contacts of the signal circuit relay 17. A resistor-capacitor circuit 18 is connected across the l2-volt battery 2 via the contacts of the master relay 1 and auxiliary switch 5. The resistor-capacitor circuit 18 is also connected between the control grid and the cathode of a discharge device, for example, a thyratron 19. 'Ihe anode of the thyratron 19 is connected via the energizing winding of a motor stop relay 20 and the contacts of master relay 1 to the positive terminal of the 45-volt battery 8. The motor of the oscillograph 9 is connected across the l2- volt battery 2 via contacts of motor stop relay 20 and master switch 3. Filaments 6a, 11a, 16a and 19a of thyratrons 6, 11, 16 and 19 respectively are connected to the l2volt battery 2 via the auxiliary switch 5. Resistors 21, 22, 23 and 24 may be included in the anode circuits of thyratrons 6, 11, 16V and 19, respectively, to limit the current passing through these discharge devices.

In the operationof the embodiment of the invention illustrated in the figure, auxiliary switch 5 is closed to heat filaments 6a, 11a, 16a and 19a of thyratrons 6, 11, 16 and 19 respectively and to apply a negative voltage via the contacts of master relay 1 to the control grids of the thyratrons 6, 11, 16 and 19, which voltage also charges the capacitors of the resistor-capacitor circuits 4, 10, 15 and 18. This negative voltage at the control grids of the thyratrons 6, 11, 16 and 19 maintains these thyratrons in a non-conducting condition for a period of time, depending upon the values of the resistor and capacitor of the associated resistor-capacitor circuit, after the respectiveg rid is disconnected from the negative terminal of the 12-volt battery 2. After the auxiliary switch 5 has been cl-osed for a period of time suicient to heat the iilaments of the thyratrons 6, 11, 16 and 19 to an operating temperature and to charge the capacitors of the resistor-capacitor circuits 4, 10, 15 and 18 to a predetermined value, the master switch 3 may be closed to begin a sequence or cycle of the seismic operation. When the master switch 3 is closed the motor of the oscillograph 9 becomes energized and drives a strip of photographic lm upon which the seismic signals are to be recorded in time-spaced relation. Furthermore, when the master switch 3 is closed the galvanometer lamps of the oscillograph 9 are extinguished or dimmed to an intensity below the threshold value for exposing the film, also, the master relay 1 becomes energized and is placed in its operative condition. When the master relay 1 is in its operative condition the contacts of the master relay 1 disconnect the control grids of the thyratrons 6 and 19 and the capacitors of thel resistor-capacitor circuits 4 and 18 from the 12-volt battery 2 and connect the anode of each of the thyratrons 6, 11, 16 and 19 to the positive terminal of the IIS-volt battery 8. As is well known, when the negative potential from'the 12volt battery 2 is disconnected from each of the capacitors of the resistorcapacitor circuits these capacitors discharge through the associated resistors of the respective resistor-capacitor circuits. The values of the resistors and capacitors of the resistor-capacitor circuits will govern the rate of discharge and hence the voltage across the capacitors at any given instant. As soon as the voltage across the capacitor of the resistor-capacitor circuit 4 is decreased to a predetermined value, thyratron 6 discharges and energizes the winding of light relay 7 which actuates its contacts to disconnect the control grid of thyratron 11 and the resistor-capacitor circuit 10 from the l2volt battery 2 and to connect the galvanometer lamps of the oscillograph 9 across the l2-volt battery 2 to fully illuminate these lamps. It can readily be seen that the time interval between the closing of master switch 1 and the discharge of thyratron 6, which is the time interval during which the motor is unreeling unexposed lm for the title block of the seismic record, can be controlled by varying the value of the capacitor of the resistor-capacitor circuit 4 or by varying the value of a resistor of the resistor-capacitor circuit 4, as shown in the drawing, or, if desired, by varying both the resistor and the capacitor of the resistor-capacitor circuit 4. After the light relay 7 disconnects the control grid of thyratron 11 and the resistor-capacitor circuit 10 from the 12-volt battery 2, the capacitor of the resistor-capacitor circuit 10 discharges in a manner similar to that described with regard to the capacitor of resistor-capacitor circuit 4. Thus, the thyratron 11 discharges at a predetermined instant after the discharge of thyratron 6, depending upon the values of the resistor and capacitor of resistor-capacitor circuit 10. Current through the discharging thyratron 11 energizes the auxiliary relay 12 which then connects the winding of the fire relay 13 across the 12-volt battery 2. When the re relay 13 operates, the negative potential from the negative terminal of the 12-volt battery 2 is disconnected from the resistor-capacitor circuit 15 and the circuit of the explosive assembly 14 is closed to fire an explosive charge of the explosive assembly 14 which creates the seismic waves in the earths formations. As shown in the figure, the auxiliary relay 12 is connected so as to operate the tire relay 13, however, these two relays may be replaced by a single relay of proper design, if desired. A predetermined time after the discharge of the explosive charge, the capacitor of the resistor-capacitor circuit 15 discharges in the manner described above in connection with the capacitors of the resistor-capacitor circuits 4 and 10 to discharge thyratron 16. The winding of the signal circuit relay 17 is then energized and the contacts of this relay close to effect desired changes in the seismic signal circuit of the oscillograph 9, for example, to increase the amplitude of the seismic signal at the oscillograph, which had been partially suppressed during the arrival of the strong primary waves to prevent overloading the apparatus, and to connect mixing circuits into the seismic signal circuit to mix signals from two or more detectors. The resistor-capacitor circuit 18 which is disconnected from the 12-volt battery 2 at the instant the master relay 1 is placed in its operative condition has a time constant sutiiciently large to maintain the thyratron 19 in its inoperative condition until after thyratron 16 has been discharged and until after a suitable length of seismic record has been recorded. When the thyratron 19 discharges,the motor stop relay 20 becomespenergized and the contacts of this relay Aopen to disconnect the motor from the l2-volt battery 2 to terminate the cycle timer automatically controls certain events of a seismic operation, including the following: (1) operates the 'oscillograph motor, without the oscillograph lights being on, for an interval of time suflicient to unreel a desired length of unexposed photographic tilm whereon a title containing data identifying the seismic record may later be added; (2) switches on the galvanometer lamps; (3) tires the explosive charge; (4) effects desired adjustments in the input of the seismic signal circuit of the oscillograph; and (5) stops the oscillograph motor after the seismic signal is recorded.

In the event of a misre, or for any'other reason, the sequence may be interrupted at any point in the cycle merely by Vopening the main switch 3 which returns the apparatus to its starting position. Then a new cycle may bel lstarted `merely by again closing the master switch 3.

After closing master switch 3 to start a cycle of operation the interval of ltime during the unreeling of a lengthV of unexposed lm is controlled by the time constant, i. e., by the Value of the resistor and capacitor, of the resisltor-capacitor-circuit 4. The interval of time'between the instant at which the lights go on, i. e., at the end of the length of unexposed iilm, and the instant at which the explosive charge is tired is `controlled by the time constant of the resistor-capacitor circuit 10. The interval of time between the instant at which the explosive charge is tired and the instant at which desired adjustments in thel spective resistor-capacitor circuit. The minimum and maximum time constants or settings of the resistor-capacitor circuits 4, 10, 15 and 18 may be, for example, 0.3-0.6 second for resistor-capacitor circuit 4, 0.04-0.11 second for resistor-capacitor circuit 10, (L15-0.46 second for resistor-capacitor circuit 15, and 3-6 seconds for resistor-capacitor circuit 18. I

In accordance with this invention the light, tire, and signal circuit relays are operated in a sequence by the series of time delay means which include the resistorcapacitor circuits 4, 10, and 15 respectively, whereas the motor stop relay is operated independently of, this series or chain by the time delay means which include the resistor-capacitor circuit 18. The operation of the time delay means of the chain and thetime delay means of the motor stop relay is simultaneously initiated at the instant when the master relay 1 is placed in its operative condition. Therefor, the motor stop relay 20 acts independently of the chain of relays 7, 13 and 6 17 so that the sequence timer will be turned 0E after a time interval determined by the time constant of resistor-capacitor circuit 18 even if one of the relays in the chain fails to function.

After the seismic signals have been recorded on the photographic film and the cycle of the seismic operation is completed, the title block may be either stamped or photographically printed on the .unexposed portion of the record. It has been found convenientto print the title block photographically after recording the seismic signals but before the photographic iilm is developed.

It should be understood that the present invention is not limited to the embodiment describedV above and that changes and modifications may occur to those skilled in the art without departing from the spirit andscope of the present invention. Furthermore, although the sequence timer has been described in conjunction with an-oscillograph-employing a photographic `filmv as av recording medium, the timer may be used also in conjunction with a magnetic tape recorder. Therefore, only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. Seismic surveying apparatus comprising anoscillograph including galvanometer lamps and a seismic signal circuit, an explosive assembly and an electronic sequence timer comprising a series of ldelay means and a plurality of switching means, each of said switching means being rcoupled to a different delay means and to a succeeding delay means of said series, said different delay means rendering said each switching means operative at alpredetermined time, said succeeding delay means being Iresponsive to said each switching means, said galvanom-` signal circuit and said explosive charge device, said resistor-capacitor circuit being connected to the input of s-aid discharge device. 3. Seismic surveying apparatus comprising an oscilograph including a motor, galvanometer lamps and a seismic signal circuit, an explosive assembly, an electronic sequence timer comprising a series of delay means and a plurality of switching means, each of said switching means being coupled to a dierent delay means and to a succeeding delay means of said series, said dierent delay means rendering said each switching means operative at .a predetermined time, said succeeding delay means being responsive to said each switching means, said galvanometer lamps, said seismic signal circuit. and said explosive assembly each being responsive to a different one of said plurality of switching means, additional delay means, means for simultaneously initiating the operation of said series of delay means, said additional delay means and said motor, and additional switching means coupled to said additional delay means land to saidmotor, said additional delay means being adapted to render said additional switching means operative'at a predetermined Hartwig et al. May 19, 1953 Wright et al. ---u May 25, 1954 UNITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION miem 21,84%;211 TU-ly' 22 1958 Thomas D., Nokefson i@ here-"oy Cozfft taat erro? appears in the ,above nwnber'ed 'patent 'foqjarng Correction tt the said Letters' Patent Should read as ggf..

In dmawgag, strike out "the Circuit ,Connection between the upper-1 moot mow-ole Contact arm o the masts? Relay l mld the next to the' uppermost movable ooRtRC-z am, of the same master' Icelay lg Column 3, lined 5A, fof tm-throng; o, ll, lo and 19, Read two-trams o, and. 19, ,and va the, Contacts of light Relay '7 and fire Relay 13 to the control grids of tfy'fatxoos 'il ard lo ospeotvely, n.,

and Cooled this 8th day of Ilo-Combat* 1959.,

l @E 1 Attest:

Ho AXLINE Attestng Officer ROBERT C. WATSON comnaasllonerk of-Patents UNITED ASTATES PATENT OFFICE CERTIFICATE 0F CORRECTION No., 2,81%:211 July 22, 1958 Thomee D., Nickerson ,above numbeied paient *ai errer' appears in the should reed as Corie 'ereby Cezetifi'e mi CokzzzieC-bioi @ad thaw the seid Let-bere' Patent I1 "512edreiv'ing, eianfike oui'J "the circuit connection between the upper moet movable cont-eet ,e-.i'm of 'the meeei relay 1 and 'the next to the uppermost move 1e e 1i-beet @im oi the seme master relay 1"; C-o1um11 3, line 54, for "p'ryw--trene 11, 16 eiic'l 19? reed m 1313371, 'brons and 19, ,and Via the Cetee of 1ig?.i"5 imeley '7 ,end fire 1Ce1ey 13 to the' Control grids of -tfryfeizl'mis 11 and 16 'f'esp'eeively, un

Signe@ sealed. this 8th dey of December' 1959.,

KARL EL, AXLINE Attesting @ffice-:r

ROBERT C. wATsoN Conmissioner of Patents 

